
import java.util.Scanner;

public class HomeWork08 {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        double x1 = scanner.nextDouble();
        double y1 = scanner.nextDouble();
        double x2 = scanner.nextDouble();
        double y2 = scanner.nextDouble();
        Straight_Line straight_line = new Straight_Line();
        straight_line.showans(x1,y1,x2,y2);
    }
}
class Straight_Line{
    Point point1 = new Point();
    Point point2 = new Point();
    public void showans(double x1,double y1,double x2,double y2){
        point1.setXY(x1,y1);
        point2.setXY(x2,y2);
        double len = Math.sqrt(Math.pow((x1-x2),2)+Math.pow((y1-y2),2));
        point1.show();
        point2.show();
        System.out.printf("line length:%.1f\n",len);
    }
}
class Point{
    private double x;
    private double y;
    public void setXY(double x,double y){
        this.x = x;
        this.y = y;
    }
    public void show(){
        System.out.printf("point:%.1f,%.1f\n",x,y);
    }
}
